The invention relates to a method for checking the plausibility of the position of the clutch actuator of a clutch contained in a dual clutch transmission. The invention also relates to a method for determining the touch point of a clutch operated by an actuator. In addition, the invention relates to a device for carrying out the method.
In modern motor vehicles, automated clutches, i.e. clutches operated by an actuator, are being used increasingly. The position of the actuating element of the clutch or of the actuator is detected in most cases with the aid of an increment meter, which directly supplies only information about actuator travel paths just traversed, but not information about the absolute position of the actuating element. In order to find the absolute position, a referencing is necessary, in which the actuator moves to a predetermined actuation position of the clutch and the current counter status of the increment meter is read.
A fundamental problem of such incremental travel measurements is their dependence on exact determination of the reference position. This problem is exacerbated by the fact that when operating a motor vehicle one must always plan on the occurrence of error events, which can result in the absolute position of the clutch actuator or of the actuating element of the clutch, and hence also the clutch torque set by the actuator in the electronic control device, no longer being known. That can result in safety-critical events, for example drive-off when travel is not wanted. Especially safety-critical is exact knowledge of the current actuating position of the clutch in a dual clutch transmission, in which two clutches must be actuated in precise coordination with each other.